一切經音義 23.57

23.57

解因自悟（因由也言辟支悟於苦無常但由自觀緣生克證不依師受故立其名為獨覺是也）。

Awakening on their own by understanding causes (解因自悟: 因 means 'by means of/originating from'. It means that a pratyekabuddha, awakening to suffering and impermanence, realizes the fruition solely by contemplating condition-arising on his own without relying on instructions from a master; hence the name 'solitary realizer' is established for him).